Traditionally flexible pipe is utilized to transport production fluids, such as oil and/or gas and/or water, from one location to another. Flexible pipe is particularly useful in connecting a sub-sea location to a sea level location. Flexible pipe is generally formed as an assembly of a pipe body and one or more end fittings. The pipe body is typically formed as a composite of layered materials that form a fluid and pressure-containing conduit. The pipe structure allows large deflections without causing bending stresses that impair the pipe's functionality over its lifetime. The pipe body is generally, but not necessarily, built up as a composite structure including metallic and polymer layers.
In many known flexible pipe designs the pipe includes one or more tensile armour layers. The primary load on such a layer is tension. In high pressure applications, such as in deep water and ultra deep water environments, the tensile armour layer experiences high tension loads from the internal pressure end cap load as well as weight. This can cause failure in the flexible pipe since such conditions are experienced over prolonged periods of time.
Unbonded flexible pipe has been an enabler for deep water (less than 3,300 feet (1,005.84 meters)) and ultra deep water (greater than 3,300 feet) developments for over 15 years. The technology enabled the industry to initially produce in deep water in the early 90's and then to ultra deep waters up to around 6,500 feet (1,981.2 meters) in the late 90's. Water depths greater than 6,500 feet push the envelope where typical free-hanging riser configurations and flexible pipe in general can operate.
It is the increasing demand for oil which is causing exploration to occur at greater and greater depths where environmental factors are more extreme. In such deep and ultra-deep water environments ocean floor temperature increases the risk of production fluids cooling to a temperature which may lead to pipe blockage. For example, when transporting crude oil blockage of the internal bore of the flexible pipe can occur due to paraffin formation. As a method to overcome such problems it has, in the past, been suggested that a layer of thermal insulation should be provided around the barrier layer of a flexible pipe, the barrier layer being the layer forming the inner bore along which fluid is transported. The thermal insulation has been somewhat effective in insulating the inner bore of the pipe from external low temperature thus helping prevent blockage. Nevertheless, the insulation effects provided have been limited.
A further problem with known insulating techniques is that the formation of insulating layers can be a complex process which involves careful alignment, heating and cooling steps during manufacture. It will be appreciated that prior known insulating techniques have appreciably increased costs and time for manufacturing flexible pipe body.
It is an aim of the present technology to at least partly mitigate the above-mentioned problems.
It is an aim of embodiments of the present technology to provide flexible pipe body which can be used in flexible pipe of a type able to transport production fluids and which includes at least one thermal insulation layer between an internal pressure sheath, such as a barrier layer or liner, and outer shield layer of the flexible pipe body.
It is an aim of embodiments of the present technology to provide flexible pipe body which includes one or more insulating layers which are simple and quick to manufacture and yet which provide a highly effective thermal resistance to impede flow of heat energy in the radial direction across the flexible pipe body.
It is an aim of embodiments of the present technology to provide a riser assembly, jumper, flowline and/or method of manufacturing a flexible pipe able to operate in deep and ultra-deep water environments.
According to a first aspect of the present technology there is provided flexible pipe body for a flexible pipe, said pipe body comprising:
an internal pressure sheath;
at least one insulating layer comprising a mesh layer comprising a plurality of pockets; and
an outer sheath.
According to a second aspect of the present technology there is provided a method of manufacturing flexible pipe body, comprising the steps of:
providing a tubular internal pressure sheath;
forming an insulating layer comprising a mesh layer comprising a plurality of pockets over the internal pressure sheath; and
forming an outer sheath layer over the insulating layer.
According to a third aspect of the present technology there is provided a method of transporting a fluid comprising the steps of:
providing a flexible pipe comprising an internal pressure sheath, at least one insulating layer comprising a mesh layer comprising a plurality of pockets, and an outer sheath; and
transporting a fluid through the flexible pipe.
The flexible pipe can be used, for example, for the extraction, transport or refining of mineral oil, crude oil or related fluids, or the transport of cold fluids, such as ammonia.
Embodiments of the present technology provide flexible pipe body in which a thermal insulation layer is formed between a barrier layer or liner and an outer sheath. One or more such insulating layers may be formed each comprising a mesh layer comprising a plurality of pockets. The mesh layer may be a weave of woven filaments with holes between filaments forming the pockets or may be a sheet of material in which the pockets are formed by a plurality of through holes or blind holes.
Embodiments of the present technology provide an insulating layer having a number of pockets in which an insulating fluid such as air or gas or some other insulating material such as aerogel material can be located.
Embodiments of the present technology provide a co-axial pipe with at least one low conductivity insulating layer between an inner and outer layer of the pipe. The insulating layer which may be a weave or punched out sheet or other such structure serves as a means of increasing the thermal resistance of the pipe wall. The interstitially insulated pipeline will decrease the thermal loss of flowing fluid such as crude oil, delaying the onset of paraffin crystallisation and delaying or preventing the deposit of solid material on an interior surface of the pipe. As a result the need to ‘pig’ the pipeline may be delayed or eliminated.
In the drawings like reference numerals refer to like parts.